Global competition compels farmers to modify cultivation practices by incorporating more cost-effective farming techniques and acquiring more efficient machinery. In doing so, farmers have increasingly turned to larger machinery and more sophisticated technology that automates and optimizes the operation of agricultural vehicles and equipment. Liquid and dry air boom type crop applicators have been used to apply a variety of crop inputs, such as fertilizer, nutrients, seed and crop protectants, herbicides, insecticides, and the like in site specific farming applications. Agricultural vehicles can apply crop inputs based on algorithms that incorporate geographical information as well as soil data, crop data, and the like to determine the amount and placement of crop inputs needed to maximize crop production.
To decrease the number of passes needed to traverse an entire field, farmers have turned to implements with increased widths, and booms extending 90 feet or more in width can now be employed. Extended booms are manufactured in hinged sections that can be controlled by a system of hydraulic cylinders to allow manipulation of individual sections. Sections can be extended outward at various angles or folded inward to avoid obstacles or minimize the space needed to store the vehicles. In addition to lateral control of the boom sections, vertical control of the boom sections can also be exercised. In many cases the terrain to be traversed by an agricultural vehicle supporting an attached implement may have sloping and uneven field conditions such as hills and terraces. The difficulties caused by uneven terrain can be exacerbated by wide-span spray booms that can create relatively large moment arms at the vehicles. For chemical spraying applications the spray nozzles mounted to the booms should preferably be positioned at uniform heights above the field or crop surface. However, when traversing a sloping field, the boom sections on one side of the vehicle may need to be raised while the boom sections on the other side may need to be lowered to maintain a relatively uniform spraying height for effective coverage. In addition, an implement too close to the ground or crop surface may damage crops or incur damage from a collision with an obstacle.
To maintain a desired boom height above the ground, boom sections can be manually raised or lowered by an operator. However, manually controlled boom operations are subject to human factor errors. Operators may not have an unobstructed view of the field in front of them, or may not be able to detect topographical changes over the entire width of area forward of the boom. In addition, operators may have delayed reaction times that prevent them from manipulating the booms quickly enough to avoid obstacles or compensate for inclines, a problem that can be exacerbated by fatigue from long hours in the field.
To avoid the problems described above, many agricultural vehicles provide means that automatically alter boom height. An array of sensors can provide real-time data that can be used to determine whether a boom section needs to be raised or lowered during a field pass. For example, sensors that can perform or assist in the performance of range-finding operations can provide information about the actual distance between the implement and the ground. However, the effectiveness of real-time sensors in driving height control commands is limited by ground speed and obstacle characteristics, and may not prevent collisions.